Understanding the Nature of Interfaces in Two Dimensional Electronic Devices(UNITE)

减小计算机中基本开关晶体管尺寸的能力正受到严重挑战。已经使用了几十年的材料，如硅，预计很快就会达到其性能的极限。这将影响需要降低功耗的应用，沿着高速开关，如便携式电子产品和手机，以及更大的功率密集型操作，如数据存储和服务器中心。该项目的国际合作研究团队将专注于确定使用这种开关的最终极限的可行性：原子级薄的二维（2D）层。被称为“过渡金属二硫属化物”的待研究材料在以原子级薄片生产时是独特的，并且表现出有希望的特性，可以实现高效的低功耗，高性能计算。将研究的一个关键特性是这些材料的表面和界面，因为它们结合在一起形成晶体管，以及这些界面的化学和物理特性如何影响和改善晶体管的电气开关行为。研究结果可以降低与驱动信息和通信时代的各种电子设备相关的功耗。这将有利于社会延长便携式设备的电池寿命，也有利于环境减少信息和通信技术消耗的总电能。该项目名为“了解二维电子器件界面的性质”，汇集了来自美国、爱尔兰共和国和北方爱尔兰的主要研究人员，每个研究人员都由各自的政府机构通过美国爱尔兰研发伙伴计划资助。该项目将为美国和爱尔兰的五名研究生提供培训，并将包括研究所之间的学生交流，为通过该项目支持的研究生提供更广泛的科学和文化经验。UNITE项目将研究用于低压隧道场效应晶体管的二维过渡金属二硫属化物半导体的合成、器件制造和表征。我们将探索两种不同的途径，通过货车德瓦尔斯外延和原子层沉积大面积合成。与此同时，表征和商业上可用的散装晶体和技术相关的接触和绝缘体之间的表面和界面区域的理解将进行。这将使用原位和非原位表征的组合来实现，所述组合涵盖以下问题：如何使2D半导体表面功能化以允许通过原子层沉积形成均匀且连续的氧化物薄膜;基于电容-电压的计量能否应用于2D半导体表面上的金属-氧化物-半导体系统; 2D半导体上的金属接触的传导性质是什么;以及原子尺度的电性质如何与较大面积的接触相关。应当注意，用于大面积衬底的生长方法的发展不仅将证明将基于2D半导体的晶体管从研究转移到生产的潜力，而且还将提供用于基础研究的技术上令人感兴趣的2D半导体材料的来源，这些材料通常不能通过地质来源获得。最后，本研究将应用于二维半导体异质结隧穿场效应晶体管的制作。如果UNITE团队能够成功理解与大面积2D合成、均匀绝缘体沉积、欧姆接触形成以及单层或多层2D半导体中的电荷传输相关的问题，这些知识将与一系列潜在的器件架构相关。

The ability to reduce the size of the basic switch in computers, the transistor, is being seriously challenged. Materials that have been used for decades, such as silicon, are anticipated to soon reach the limit of their performance. This will impact applications where reduced power is needed, along with high speed switching, such as portable electronics and cell phones, as well as larger power intensive operations, like data storage and server centers. The collaborative international team of researchers in this program will focus on determining the feasibility of using the ultimate limit for such switches: atomically-thin, two-dimensional (2D) layers. The materials to be studied, called "transition metal dichalcogenides," are unique when produced in atomically thin sheets, and exhibit promising properties that may enable efficient low power, high performance computing. A key property that will be studied is the surface and interfaces of these materials as they are combined to form the transistor, and how the chemical and physical properties of these interfaces impact and improve the transistor electrical switching behavior. The research results could enable the possibility of reducing the power consumption associated with the broad spectrum of electronic devices, which drive the information and communication age. This will be good for society in terms of extended battery life in portable devices and also good for the environment in terms of reducing the total electrical energy consumed by information and communication technologies. The project, entitled "Understanding the Nature of Interfaces in Two-Dimensional Electronic Devices (UNITE)," brings together leading researchers from the USA, the Republic of Ireland and Northern Ireland, each funded by their respective government agencies through the US Ireland R&D Partnership Program. The project will provide training to five graduate students in the USA and Ireland, and will include student exchanges between the Institutes providing a broader scientific and cultural experience for the graduate students supported through the project.The UNITE project will investigate the synthesis, device fabrication and characterization of 2D transition metal dichalcogenides semiconductors for applications in low voltage tunnel field effect transistors. We will explore two separate routes to large area synthesis through van der Waals epitaxy and atomic layer deposition. In parallel, characterization and understanding of the surfaces and interfacial regions between commercially available bulk crystals and technologically relevant contacts and insulators will be conducted. This will be accomplished using a combination of in-situ and ex-situ characterization covering questions such as: how can 2D semiconductor surfaces be functionalized to allow uniform and continuous oxide thin films to be formed by atomic layer deposition; can capacitance-voltage based metrology be applied to metal-oxide-semiconductor systems on 2D semiconductor surfaces; what is the nature of conduction for metal contacts on 2D semiconductors; and how are the atomic scale electrical properties related to larger area contacts' It is noted that the development of growth methods for large area substrates will not only demonstrate the potential to move 2D semiconductor based transistors from research to production, but will also provide a source of technologically interesting 2D semiconductor materials for basic study which are not commonly available through geological sources. Finally, the growth and characterization studies will be applied to the fabrication of a tunnel field effect transistor based on two dimensional semiconductor heterostructures. If the UNITE team can successfully understand the issues relating to large area 2D synthesis, uniform insulator deposition, ohmic contact formation, and charge transport in single or few layer 2D semiconductors, this knowledge will be relevant to a range of potential device architectures.